When I arrived in Chicago for a visit in the spring of 2007, the first thing I noticed was that a loud buzzing noise filled the air. The city seemed to be suffering from an overwhelming invasion of singing, red-eyed, and locust-like insects. The bugs crunched beneath my feet as I walked through Millennium Park, and dropped onto my shoulders as I strolled beneath tree branches. I was witnessing the return of the cicadas, an event that only occurs once every 17 years!
These remarkable insects were periodical cicadas, some of the longest-lived bugs in the world. While cicadas hatch within tree branches, upon entering the world they almost immediately begin to dig, burrowing themselves underground where they can feed upon the fluids in plant roots. Here, in the dark earth, they spend the majority of their years. When they are finally ready to mate, 17 years later, they emerge in staggering numbers, overrunning the landscape in a manner reminiscent of a biblical plague.
The Cicada Love Song
The high-pitched song that I heard upon arrival was actually the cicada mating call, which the males make by vibrating membranes on their abdomens. Astonishingly, this song can exceed 120 decibels if heard at close range! As a result, many find the cicadas’ songs quite disturbing. Males also tend to group themselves together in order to amplify the sound, since this repels potential bird predators.
Once males have mated, they almost immediately die. Females then depart to distribute as many as 600 eggs each throughout the surrounding trees. Shortly after laying all of their eggs, females also die. The entire process takes about 30 days.
Preparing for Cicada Infestations
The sight of such an enormous number of bugs emerging from the ground all at once is frightening for some, and fascinating for others. So, should you be concerned if you are in an area slated for a cicada invasion? Are there any precautions that you should take? Fortunately, these creatures neither bite nor sting, and cause limited damage to gardens. When females lay eggs, they cut two small slits in tree branches or bushes, and then lay the eggs inside the slits. Therefore, young trees and small bushes do sometimes suffer from cicada invasions, though older trees usually recover quickly. If you wish to protect a bush from cicada attack, wrap the bush completely in insect netting, and be sure to seal up the area around the base.
The 17 year cicadas are only one of many different types of cicadas. Others have 13 year cycles, while still others have multi-year life cycles, but emerge annually. Cicada cycles vary from region to region, so while you won’t be able to observe another such invasion in Chicago until 2021, states ranging from North Carolina to New York along the East Coast are scheduled to experience their next cicada invasion in 2013.